Spoilers: How that unexpected 'F9' end-credits scene sets up 'some unfinished business'

Spoiler alert: This story discusses important plot points and the ending of “F9,” so beware if you haven’t seen it yet.

Not only did “F9” take the “Fast and Furious” franchise to space – come on, you knew it was only a matter of time – but the action extravaganza reunited estranged brothers, settled an old score and paid tribute to one actor’s lasting legacy.

Naturally, our hero Dominic Toretto (Vin Diesel) and his crew once again saved the world from a dangerous threat in various over-the-top ways, keeping the villainous hacker Cipher (Charlize Theron) from taking over weapons systems across the globe with the Project Ares device. (Helpful in that effort is a Pontiac Fiero that jets into orbit and then runs over a satellite. No, really.)

The new film also fixed a feud between Dom and his forsaken little brother, rogue superspy Jakob Toretto (John Cena). After years blaming Jakob for their father’s death, Dom found out it wasn’t his fault, saved his bro after a betrayal and began a process of forgiveness. Jakob also drove off into the sunset so they can (perhaps) team up again in the upcoming 10th “Fast” flick.

But one of the biggest events is the return of Han Lue (Sung Kang), who was presumed dead in a fiery car crash (see: “Tokyo Drift” and “Fast & Furious 6”). Kang and “F9” director Justin Lin break down the major spoilers from the new film:

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Cardi B enters the ‘Fast’ fray – and not just for one cameo

The franchise has had musical guest stars in the past, from Ja Rule to Rita Ora to Iggy Azalea, though Grammy-winning rapper Cardi B is arguably the most A-list. When Dom goes to London to face Jakob, his bro’s villainous benefactor (Thue Ersted Rasmussen) calls Interpol on Dom, who gets thrown in a paddy wagon. However, one of the agents is Leysa (Cardi B), a woman on the inside whom Dom knows from way back and is now working for Queenie Shaw (Helen Mirren). It’s not just a one-off, either, as Cardi B is on tap to reprise her role in “Fast 10.”

When Lin directed “Tokyo Drift,” “you couldn't get people on the phone, and then as we grew as a franchise, we're getting incoming calls,” the filmmaker says. “I never know who's on the other end of that call, and in this case, I remember Vin coming in and he says, ‘Cardi B. What do you think?’ And I'm like, ‘Great! I think it would be a really great addition.' Now to be able to get to work with her for a little bit, there's so much more that we can explore down the road.”

Paul Walker’s Brian O’Conner lives on at the movies

After saving the day, Dom brings everybody home for the usual celebratory Toretto barbecue. There’s an empty plate and seat at the table, and a familiar Nissan Skyline arrives in the driveway before the credits roll.

Even though Paul Walker died in 2013 during production on “Furious 7," his character Brian O’Conner still exists onscreen: He was presumably watching the kids while Dom and his sister Mia (Jordana Brewster), Brian’s girlfriend, handled business.

“The decision to keep Brian in the ‘Fast’ universe is an important one,” Lin says. “I constantly make sure I have conversations, even with myself, that no matter what we do moving forward, the acknowledgement of Brian is done in a way that is respectful.”

Sung Kang's Han returns to life with a new reason for being

Kang’s snack-happy racer seemed to meet a fiery end a few movies ago, though an early “F9” trailer revealed his reappearance. Now we know what happened: Han was recruited by intelligence operative Mr. Nobody (Kurt Russell) to be his man in Tokyo, so he faked his death and lived in the shadows protecting Elle (Anna Sawai), an orphaned girl tied to Project Ares.

Being a parental figure gives Han “a different reason to wake up in the morning,” Kang says. “I really appreciated being able to play a character that is responsible for someone other than himself." The actor doesn't have children in real life, but when I meet other men that are fathers, they have a different swagger about them. There's a different level of confidence and purpose that I envy, I admire and I would go, ‘I wish I had that.’

“The beauty of being an actor is that even if you're not able to experience that in real life, you get a little piece of it while you play pretend.”

Deckard Shaw sees a ghost in the 'F9' end-credits scene

Jason Statham’s mercenary is the man who took responsibility for Han’s death. But after a throwdown in "Furious 7," he's been uneasy allies with Dom as well as Dwayne Johnson’s lawman Luke Hobbs (as seen in the spinoff “Hobbs & Shaw”). Shaw is also the guy we see in the extra scene at the end of “F9”: In a warehouse, he’s going to town on a punching bag – as it turns out, there’s a dude crammed inside that he’s pounding – when a knock at the door interrupts him. Shaw opens the door, and he’s shocked to see Han standing in front of him.

There’s still a question whether Shaw was part of Nobody’s ruse, but doing that scene was “the coolest thing,” says Kang, who co-starred with Statham in 2007’s “War.” “To be able to share the screen with him and have him in this universe is awesome. And now to be able to continue hopefully some unfinished business (with him) is even cooler.”

Lin adds there’s a lot more story with Han, and he wants to honor the #JusticeForHan movement formed in the fan community. “It's not about bringing him back to life, but it is to promise that we're always going to treat him with respect.”